Reversible gravity concrete or mortar mixer



April 15, 1969 I U P. AUGUST 3, 3 ,6 3 I REVERSIBLE GRAVITY CONCRETE OR MORTAR MIXER Filed April 14, 1966 M/X/NG INVENTOR PAUL AUGUST Attorneys United States Patent Int. 01. B28c 5/18, 7/16 U8. (:1. 259-162 4 Claims The invention is concerned with a reversible gravity mixer, of the kind (referred to hereinafter as the kind referred to) disclosed .in my prior Patent No. 3,145,977, issued Aug. 25, 1964 wherein discharge of the mixture takes place by reversal of the motor and in which all operations, such as rotation of the mixing-drum, reversal of the mixing-drum and raising and lowering of the elevator bucket, are undertaken by a single motor, the elevator bucket being operated by a winch or other raising or lowering means which is locked, in one direction of rotation only, by means of a free-wheel.

Most reversible gravity mixers, and also even some positive-control mixers, possess tWo or even three drivingmotors, and are push-button controlled. One motor effects rotation of the mixing-drum and another pulls the feedbucket up and lowers it again. With positive-control mixers, a third motor controls the opening with which the discharge-slide co-operates.

The provision of these two motors and the control gear therefor is expensive, and considerably adds to the cost of the mixer. Various proposals have already been made for the simplification of these known constructions.

According to one such proposal, as disclosed in the aforesaid patent, provision is made between the motor and the drive for the mixing-drum, for a winch for the feedbucket, which winch fits, however, on a free-wheel. This free-wheel locks when, in a gravity mixer, the mixingdrum revolves in the discharge direction. At the same time, by means of the locked free-wheel, the feed-bucket is drawn up, it charges the mixing-drum upon completion of the preceding discharge operation and, in its highest position, it switches off the motor by means of a limit switch. Upon the direction of rotation of the motor changing, and with it the beginning of the mixing operation, the feed-bucket drops down again, under the control of the motor. However, this arrangement still possesses some disadvantages, which sometimes affect the mixing sequence unfavorably.

When comparatively dry concrete is being mixed, the drum must be swilled out with water after each mixing operation, so that no residues remain stuck to the mixing paddles and the inner drum-wall. This is not possible with the existing arrangement.

The operation of feeding from the bucket into the mixing-drum is comparatively brief, and only a few seconds after the start of the feed operation the drive for the drum is switched off so that the drum is at rest. This means that with a mixture which is not of a free-flowing or freerolling nature, a blockage occurs and the feed-bucket cannot be fully emptied.

It is an object of the invention to provide a mixer with which the above-mentioned disadvantages will be avoided.

According to the invention a transmission including reversing gear is inserted adjacent the winch or other means provided for raising and lowering the feed-bucket, this transmission being driven by a sprocket-wheel, gear-wheel or other driving element, and a free-Wheel is fitted between the said driving element and the driving-shaft of the motor. With this arrangement it is possible after each mixing operation to add water and wash out the mixingdrum, before the feed-bucket delivers the charge to the 3,438,613 Patented Apr. 15, 1969 mixer. The feed-bucket can therefore be loaded when the mixer has already been running in the mixing direction for some while. Thus, the mixing-rnachine accepts the new mixture in a better manner, and no blockages are caused. The feed-bucket empties itself equally as well as with mixers with two motor drives.

Advantageously provision is made for the output-shaft of the transmission to have different rates of rotation depending on its direction of rotation. The empty feedbucket can then be lowered at a greater speed than is possible when the filled feed-bucket is being raised. Because of that, substantially more time becomes available for filling the feed-bucket.

Further features of the invention and details of the advantages arising therefrom will be apparent from the following description with reference to the accompanying drawing, which shows, by way of non-limitative example only, one form of drive means for a mixer according to the invention.

Referring to the drawing, a drive motor 1 drives, through a clutch 2, drive rollers 11 and 12 for a mixingdrum. Between the clutch 2 and the drive rollers there is a sprocket-wheel 3, which is mounted on a drum 4. This drum is mounted, by means of a free-wheel and bearings, on a shaft 6, which also carries the drive rollers 11 and 12 for the mixing-drum which is only diagrammatically shown in the drawing but which is well known in the art, as exemplified by my above patent. A transmission 8, including changeover or reversing gear, is mounted alongside, and carries a sprocket-wheel 5 on an input shaft 13 and a winch 9 on an output shaft 7. A chain C connects the sprocket-wheels 3 and 5. In place of the two sprocketwheels, V-belt pulleys, gear wheels, or other power transmission elements can of course be used.

The transmission 8 includes a changeover coupling which can directly connect the input shaft 13, to which the sprocket-wheel 5 is fitted, to the output shaft 7, to which the winch 9 is fitted. If the coupling is changed over, then, by way of the intermediate shafts and gear wheels, the direction of rotation of the output shaft, to which is fitted the winch 9, is altered. Preferably, the speed of the output shaft will also be increased at the same time, by means of appropriate gearing. A lever L actuates the coupling so that in, for instance, the position 10, the coupling directly connects the input and output shafts, while in position 10' the lever L serves to bring into action the reversing gear. Moreover, movement of the lever L from position 10 to position 10' is directly effected by the feedbucket 21 in its highest position, by means of a rope 26 or a rod-linkage. The winch 9 receives a rope or cable 14 which, in one direction of rotation, pulls the feedbucket 21 up and which in the other direction lowers it. The rope 14 passes over one or more direction changing pulleys 15, 16, 17, 18 and 19 and is connected to a cross rod 20 which is attached to the elevator bucket or charging tub 21. The bucket 21 is connected via a control means 25 to a rope or cable 26 which is connected to the lever L.

The manner of operation of the mixer and of the drivearrangement will now be further explained.

In the direction of rotation of the mixing-drum in which the drum is emptying, the free-wheel is not engaged, and it does not drive the sprocket-wheel 5. When discharge of the mixing-drum is completed, the motor is switched over, so that the drum is set in the rotational direction for mixing. In this direction the free-wheel locks and, through the sprocket-Wheels 3 and 5, drives the input shaft 13 of the transmission, which shaft is directly connected through the coupling provided by the transmission, to the output shaft 7. The shaft 7 and its winch 9 rotate and pull the rope or cable 14 which in turn pulls on the cross rod 20 and raises the feed-bucket 21. In the meantime water has already been introduced into the mixing drum, so that the inside of the mixing-drum is washed out during the time in which the feed-bucket is being drawn up. When the feed-bucket reaches its highest position in which it has already delivered the material to the mixing-drum, it exerts an operating pull on the cable 26 through the control means 25 actuated by the movement of the bucket in arriving at its highest position and the cable 26 switches the lever L from position to position 10. In this way the reverse gear is engaged and the feedbucket is lowered again under its own weight. Should it tend to go down faster than is permitted by the speed of.

the motor, it is restrained by the free-wheel and is prevented from falling. Thus, it is lowered under the control of the motor. Because the empty feed-bucket can go down faster than the full bucket can be brought up, the gearing for reverse rotation is preferably so selected, that the output shaft 7 runs faster in this direction of rotation. The empty bucket gets down sooner, and one gains more time for re-charging it. The rope which draws the feedbucket up and lets it down is guided by guide pulleys and is wound around the winch 9.

While the feed-bucket is being replenished with mixture at its lowered position, the drum mixes the previously delivered batch. On completion of this operation, the motor is switched over, and the mixing-drum emptied. On completion of discharge, the motor is switched off again, and at the same time the lever is pushed from position 10 to position 10. On switching the motor on again in the direction of rotation in which the mixing-drum mixes, the identical charging-process starts again from the beginning, whereupon the feed-bucket itself in its highest position automatically switches over the transmission 8 in order that the feed-bucket can travel down again.

This whole operation is of course only possible if a free-Wheel is inserted between the driving shaft 6 for the mixing-drum and the transmission 8, so that upon setting down the feed-bucket at the bottom, the winch 9 does not rotate any further, and also so that during discharge of the mixing-drum, that is to say during the opposite direction of rotation of the motor, driving of the transmission cannot take place at all. With this arrangement, the disadvantages of normal single motor mixers as known hitherto are removed; in such mixers the operator had to use couplings and levers to hold the feed-bucket during lowering, by means of a friction clutch, so that, on the one hand, the attention of the operator was taken up for this time and, on the other hand, with poor supervision, the feed-bucket might fall down, which happened frequently and caused damage. Moreover, an enormous amount of wear of the couplings took place. Such an arrangement is not at all possible with, for instance, a cradletype construction for the feed-bucket, such as is more and more in demand. These advantages are also the reason that almost all modern mixers have push-button-controlled two motor drives, even though this is usually about 20% more expensive than the single motor drive.

The disadvantage of the two motor drive, namely the 20% additional expense due to the second motor, which has a transmission and brake, and to the extra controls, is avoided with the arrangement according to the invention. The added transmission is no more expensive than the couplings used with the single motor drive, but it functions completely automatically as regards reversal of the bucket, and also the bucket is firmly under the control of the motor during its descent.

With the invention it is possible to supply water to and to wash out the mixing-drum after each mixing operation, before the feed-bucket is recharged. If lever 10 is not moved over, the feed-bucket stays at the bottom, and the mixing-drum can get a prolonged wash, or can be cleaned at the end of the working day.

When the mixing-drum is being charged it is already revolving in the direction for mixing. It therefore accepts the new ingredients in a better manner, and blockages do not occur. The feed-bucket empties itself equally as well as with normal mixers having two motor drives. Thus all the advantages of semi-automation and positive control of the feed-bucket are obtained, as with machines having two motor drives.

With the drive arrangement according to the invention, substantial progress in the field of building economics has "been achieved, not only from the point of view of saving prime costs, but also from the point of view of insuring that running costs are kept low. Moreover, the mixing operation can proceed uninterruptedly without loss of time and without idle periods.

What I claim is:

1. A reversible gravity mixer for concrete and mortar, comprising rotatable supporting means on which a rotary mixing drum is adapted to be rotatably positioned for rotation thereby, a single motor having a driving shaft selectively rotatable in opposite directions of rotation, means operatively connecting the drive shaft in one direction of rotation thereof to the rotatable supporting means for effecting an emptying movement of the mixing drum and in the other direction of rotation thereof to the rotatable supporting means for effecting a rotational movement of the mixing drum for mixing a charge therein, a free wheel operatively associated with the drive shaft and adapted to be .actuatably locked therewith when it rotates in such other direction of rotation, a transmission means having an input and an output shaft and having a drive coupling arrangement drivingly coupling said shafts and including a selectable reversing gear, a winch operatively connected to and driven by the output shaft and having a cable means adapted to be connected to an elevator bucket for charging the mixing drum, a driving element carried by the input shaft and to which the free wheel is drivingly connected for driving the input shaft in one direction of rotation, and means operatively connected to the transmission means for controlling the direction of rotation of the output shaft, said last means being operative in one position for causing the input and output shafts to rotate in the same direction so as to drive the winch in a direction to effect a lifting movement of the elevator bucket in charging the mixing drum and being operative in a second position when such bucket reaches its highest movement so as to cause the reversing gear to be operative and effect a rotation of the output shaft in an opposite direction from the input shaft whereby the bucket is lowered under the control of the motor.

2. The invention defined in claim 1 wherein the output shaft rotates at a faster speed when the reversing gear is operative and the output shaft is rotating in an opposite direction from the input shaft.

3. The invention defined in claim 1 wherein said last means includes an actuating lever which is manually settable in the one position and is operatively connected to the elevator bucket and adapted to be actuated thereby in causing the reversing gear to be operative.

4. The invention defined in claim 1 wherein said free wheel is carried by the drive shaft.

References Cited UNITED STATES PATENTS 3,145,977 8/1964 August 259-167 X FOREIGN PATENTS 126,298 9/1949 Sweden.

ROBERT W. JENKINS, Primary Examiner.

US. Cl. X.R. 259167, 177 

1. A REVERSIBLE GRAVITY MIXER FOR CONCRETE AND MORTAR, COMPRISING ROTABLE SUPPORTING MEANS ON WHICH A ROTARY MIXING DRUM IS ADAPTED TO BE ROTATABLY POSITIONED FOR ROTATION THEREBY, A SINGLE MOTOR HAVING A DRIVING SHAFT SELECTIVELY ROTATABLE IN OPPOSITE DIRECTIONS OF ROTATION, MEANS OPERATIVELY CONNECTING THE DRIVE SHAFT IN ONE DIRECTION ROTATION THEREOF TO THE ROTATABLE SUPPORTING MEANS FOR EFFECTING AN EMPTYING MOVEMENT OF THE MIXING DRUM AND IN THE OTHER DIRECTION OF ROTATION THEREOF TO THE ROTATABLE SUPPORTING MEANS FOR EFFECTING A ROTATIONAL MOVEMENT OF THE MIXING DRUM FOR MIXING A CHARGE THEREIN, A FREE WHEEL OPERATIVELY ASSOCIATED WITH THE DRIVE SHAFT AND ADAPTED TO BE ACTUATABLY LOCKED THEREWITH WHEN IT ROTATES IN SUCH OTHER DIRECTION OF ROTATION, A TRANSMISSION MEANS HAVING AN INPUT AN OUTPUT SHAFT AND HAVING A DRIVE COUPLING ARRANGEMENT DRIVINGLY COUPLING SAID SHAFTS AND INCLUDING A SELECTABLE REVERSING GEAR, A WINCH OPERATIVELY CONNECTED TO A DRIVEN BY THE OUTPUT SHAFT AND HAVING A CABLE MEANS ADAPTED TO BE CONNECTED TO AN ELEVATOR BUCKET FOR CHARGING THE MIXING DRUM, A DRIVING ELEMENT CARRIED BY THE INPUT SHAFT TO WHICH TO FREE WHEEL IS DRIVINGLY CONNECTED FOR DRIVING THE INPUT SHAFT IN ONE DIRECTION OF ROTATION, AND MEANS OPERATIVELY CONNECTED TO THE TRANSMISSION MEANS FOR CONTROLLING THE DIRECTION OF ROTATION OF THE OUTPUT SHAFT, SAID LAST MEANS BEING OPERATIVE IN ONE POSITION FOR CAUSING THE INPUT AND OUTPUT SHAFTS TO ROTATE IN THE SAME DIRECTION SO AS TO DRIVE THE WINCH IN A DIRECTION TO EFFECT TO LIFTING MOVEMENT OF THE ELEVATOR BUCKET IN CHARGING THE MIXING DRUM AND BEING OPERATIVE IN A SECOND POSITION WHEN SUCH BUCKET REACHES ITS HIGHEST MOVEMENT SO AS TO CAUSE THE REVERSING GEAR TO BE OPERATIVE AND EFFECT A ROTATION OF THE OUTPUT SHAFT IN AN OPPOSITE DIRECTION FROM THE INPUT SHAFT WHEREBY THE BUCKET IS LOWERED UNDER THE CONTROL OF THE MOTOR. 